This invention pertains to a pin register control board for the creation of multiple images. In particular, it pertains to a step and repeat board for moving an image horizontally and vertically in a highly accurate manner whereby two or more images of the same copy material are formed on spatially distinct regions of a light sensitive emulsion.
The lithographic process commonly involves printing of an image of desired copy material onto paper or other medium of choice. A plate carrying at least one image of copy is attached to a rotating cylinder of a printing press. Upon rotating the cylinder, the attached plate is inked and the images on the plate are printed onto the paper.
The image on the plate results by exposing the developed emulsion, i.e. a negative or positive image, onto the plate used by the printing press.
When creating successive images of desired copy material, each image must be in exact register with the registration system. Multiple images are then created by sequentially exposing light sensitive material through negatives or positives in a conventional vacuum frame exposure system. It is necessary that the copy maintain exact alignment through the multiple exposures. Only by so doing is it possible to achieve dot-for-dot registration and a perfect production of every line and dot over the entire image.
In many cases, the image formed on a frame of film or the image formed on a plate, is small in size relative to the film frame or plate. In these cases, portions of the film frame or plate may be inefficiently left unused in lithographic process. Because great expense attends the use of lithographic presses, and the paper printed by such presses is also very expensive, it is desirable to use plates bearing multiple identical images to create multiple printed copies from one turn of the cylinder in a printing press. The number of multiple identical images possible is dependent on the size of the subject matter relative to the plate or film. In most instances with the desire to completely fill a plate it is necessary to sequentially expose images both horizontally and vertically.
A common prior art approach involves the stepped use of a single item of copy in order to produce two or more such images. This is referred to as a "step and repeat" process or procedure. While only a single image is used, or multiple images for color and some black and white work, the step and repeat procedure in use today is very labor intensive and concomitantly expensive. A masking sheet or substrate is extended across the board, top to bottom, preferably with some registration control. To reposition the image vertically the image must be removed from the substrate and restripped to move it up or down for the next image.
Proper alignment of the printed image relative to printed material is important for printing from plates bearing multiple images. Continuity of register control, i.e. carrying backward and forward throughout the lithographic process the proper alignment of images, is important for multiple image printing. It is desirable that the continuity of register control reach backward in a lithographic process to the step where multiple images are first assembled from a single item of copy.
The prior art shows the use of register pins for maintaining continuity of register control, but shows such use primarily for single images. Prior step and repeat procedures have been very labor intensive and have required the repeated repositioning of images on multiple substrates or vehicles to obtain horizontal and vertical positioning with the accuracy required.
There is a need for a simple step and repeat procedure which is not labor intensive and which can yield two or more images of the same subject matter imposed upon spatially distinct regions of a single frame or plate. There is also a need for continuity of register control in forming these multiple images. Step and repeat boards that could position the single image of the copy or subject matter horizontally and vertically in a highly accurate and rapid manner would be a significant advantage.